WASHINGTON — Building the $5.3 billion Keystone XL oil pipeline across the middle of the United States will require thousands of workers and millions of pounds of steel. It will also require a lot of smelly dead rats. The U.S. Fish & Wildlife Service this month said that Keystone's proposed route across Nebraska put the endangered American burying beetle at risk. The agency said the black and orange-spotted insect could be spared, and the project move forward, if proper procedure is followed. That means pipeline builder TransCanada Corp. will have to trap and relocate the one-inch beetles, using frozen rats...